This invention relates to an internal combustion and more particularly to an improved camshaft arrangement for such engine.
As is well known, four cycle internal combustion engines have a valve actuating mechanism for the poppet valves that serve each of the combustion chambers. These camshafts are journaled in an engine body for rotation about an axis that is generally parallel to the crankshaft axis and which is driven at one half crankshaft speed. The camshaft has individual cam lobes that are associated with the actuated valves and which operate the valves through a suitable mechanism. This may include push rods and rocker arms or direct action, for example, via thimble tappets.
In either event, the construction of the camshaft generally is comprised of a cylindrical main body and a plurality of individual cam lobes for the purpose aforenoted. The inherent construction of the cam lobes, however, gives rise to its certain unbalances in the camshaft. That is, the cam lobes are not always symmetrically placed and thus may present off center masses that can cause out of balance forces that can cause vibration.
It is, therefore, a principle object of this invention to provide an improved camshaft construction for an engine.
It is a further object of this invention to provide a more balanced camshaft for operating the valves in an internal combustion engine.
The cam shaft has, in addition to its lobes, a main body portion from which the lobes protrude and also bearing areas along its length for the rotational support in the associated engine body. Normally the main body portion has an outer diameter that is uniform between the lobes and bearing areas. This main body portion is only slightly smaller in diameter than that of the bearing areas. Thus the cam shaft has substantial mass. This is undesirable for several reasons.
It is, therefore, a still further object of this invention to provide a lighter weight, balanced camshaft for an internal combustion engine.